Charge and Energy Noise from On-demand Electron Sources

Licentiatavhandling, 2018

On-demand single electron sources (SES) are of key importance for future electronic applications such as metrology or quantum optics with electron. They allow for achieving a controlled, low-fluctuations flow of particles in a coherent mesoscopic conductor. One way to characterize the precision and spectrum of the injected single-particle state from these sources is to study correlations of charge- and energy currents.

We analyze a prominent example for such single-electron sources which is the emission of single electrons from a driven mesoscopic capacitor in the quantum- Hall regime. By employing the Floquet scattering approach, we study the features of this source in charge- and energy-current noise. Whereas the charge-current noise is proportional to the number of emitted particles, the energy-current noise is sensitive to properties of the driving potential. When the mesoscopic capacitor is driven slowly, we compare its features with the application of a Lorentzian- shaped, time-dependent potential to a coherent conductor. Both sources emit exactly the same pulse but with different type and number of particles.

In contrast to charge currents, energy currents and their fluctuations are more difficult to access experimentally. We theoretically propose a setup for the detection of fluctuating charge and energy currents, as well as their correlations, generated by an arbitrary time-dependently driven electronic source. Employing the Boltzmann-Langevin approach, we show that these fluctuations are detectable through a read-out of frequency-dependent temperature and electrochemical-potential fluctuations. We discuss the feasibility of our detection scheme for a concrete example of the mesoscopic capacitor setup in the quantum Hall regime. Finally, we review different, experimental-related aspects that should be taken into account when optimizing the proposed detection scheme.